During unscripted speech, speakers coordinate the formulation of pre-linguistic messages with the linguistic processes that implement those messages into speech. We examine the process of constructing a contextually appropriate message and interfacing that message with utterance planning in English ("the small butterfly") and Spanish ("la mariposa pequena") during an unscripted, interactive task. The coordination of gaze and speech during formulation of these messages is used to evaluate two hypotheses regarding the lower-limit on the size of message planning units, namely whether messages are planned in units isomorphous to entire phrases or units isomorphous to single lexical items. Comparing the planning of fluent pre-nominal adjectives in English and post-nominal adjectives in Spanish showed that size information is added to the message later in Spanish than English, suggesting that speakers can prepare pre-linguistic messages in lexically-sized units. The results also suggest that speakers can use disfluency to coordinate the transition from thought to speech. (Contains 4 figures and 2 tables.)